An information transmission system including a packet switching network provided with terminals to which stations are coupled, at least one station being able to provide a plurality of information signals in the form of packets asynchronously and on a time division basis to its associated transmitting terminal, and at least one other station being able to process the packet sets received at its associated receiving terminal, is already known from the article "Asynchronous Time Division Networks: Terminal Synchronization for Video and Sound Signals, by J-Y Cochennec et al, Globecom '85, IEEE Global Telecommunications Conference, New Orleans, La. December 2-5, 1985, pp. 791-794".
In the system described in that article, in certain cases, e.g., real-time transmissions of video images, it is not possible to request the repetition of a lost packet and thus special measures have to be taken to compensate for the effect of such a loss. These measures for instance consist in replacing a line of a video image signal affected by the packet loss by the same line of a previous image.
The transmission of information signals one after the other which define versions of different accuracy of the same image and the combination of these successive signals in a receiving station are known per se from the article "Making Progressive Transmission Adaptive" by W. D. Hofmann and D. E. Toxel, published in IEEE Transactions on Communications, Vol. COM. 34, No. 8, August 1986, pp. 806-813.